>Hi
>I have review the yaffs2 source code and have a doubt. See the follow
>In Yaffs2 the read interface is yaffs_rd_chunk_tags_nand int yaffs_rd_chunk_tags_nand(struct yaffs_dev *dev, int nand_chunk,
> u8 *buffer, struct yaffs_ext_tags *tags) {
> .........
> result = dev->tagger.read_chunk_tags_fn(dev, flash_chunk, buffer, tags);
> if (tags && tags->ecc_result > YAFFS_ECC_RESULT_NO_ERROR) {
>
> struct yaffs_block_info *bi;
> bi = yaffs_get_block_info(dev,
> nand_chunk /
> dev->param.chunks_per_block);
> yaffs_handle_chunk_error(dev, bi);
> }
> return result;
>}
>
>The yaffs_rd_chunk_tags_nand will call the mtd interface mtd_read_oob
>int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops) {
> int ret_code;
> ops->retlen = ops->oobretlen = 0;
> if (!mtd->_read_oob)
> return -EOPNOTSUPP;
> /*
> * In cases where ops->datbuf != NULL, mtd->_read_oob() has semantics
> * similar to mtd->_read(), returning a non-negative integer
> * representing max bitflips. In other cases, mtd->_read_oob() may
> * return -EUCLEAN. In all cases, perform similar logic to mtd_read().
> */
> ret_code = mtd->_read_oob(mtd, from, ops);
> if (unlikely(ret_code < 0))
> return ret_code;
> if (mtd->ecc_strength == 0)
> return 0; /* device lacks ecc */
> return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0; }
>So if the bitflips num over mtd->bitflip_threshold the mtd_read_oob will return -EUCLEAN and tags->ecc_result > YAFFS_ECC_RESULT_NO_ERROR.>
>Then we will call yaffs_handle_chunk_error.
>void yaffs_handle_chunk_error(struct yaffs_dev *dev,
> struct yaffs_block_info *bi)
>{
> if (!bi->gc_prioritise) {
> bi->gc_prioritise = 1;
> dev->has_pending_prioritised_gc = 1;
> bi->chunk_error_strikes++;
>
> if (bi->chunk_error_strikes > 3) {
> bi->needs_retiring = 1; /* Too many stikes, so retire */
> yaffs_trace(YAFFS_TRACE_ALWAYS,
> "yaffs: Block struck out");
>
> }
> }
>}
>From the code we can see if bitflips num over mtd->bitflip_threshold we will mark this block as gc if bitflips num over mtd->bitflip_threshold over three times we will mark this block as bad block.
>We define bad block is if erase or program failed we can mark this block as bad block.
>So is it reasonable just according to the bitflips over mtd->bitflip_threshold over three times to judge the block as bad block?
>What's your opinion about my doubts?
Hi clarles,
Do you have any proposal about this?
Br
White Ding
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